- Glaubenberg planning territory
This planning territory largely follows the existing 220 kV line and leads from Innertkirchen via Giswil and Glaubenberg to Malters and then on towards Mettlen. The greatest challenge of this option is the «Glaubenberg» flysch moor landscape. No overhead lines or underground cables installed using open trenching techniques are permitted in this landscape of national importance. Swissgrid therefore proposes to tunnel under Glaubenberg.
- Pilatus planning territory
The second option leads from Giswil through the Sarneraa Valley and then west or east of Pilatus to Littau and Mettlen. The main challenges presented by this option are the large settlement areas (Giswil, Sarnen, Alpnach, Hergiswil and Kriens), the scattered settlements, and the limitations imposed by the obstacles of the Kägiswil, Alpnach and Buochs airfields and the nationally protected Pilatus region.
- Entlebuch planning territory
As a third alternative, a planning territory could lead west from Giswil through Entlebuch to Mettlen. This option crosses through the UNESCO Entlebuch biosphere reserve and is much longer than the two other evaluated planning territories.
Swissgrid recommends the Glaubenberg planning territory
Both of the submitted variants have specific advantages and disadvantages with respect to regional planning, the environment, technology and economic viability. From Swissgrid’s perspective, the Glaubenberg planning territory provides is the best of the three options. Firstly, it touches fewer settlement areas and involves fewer obstacles than the other options. Secondly, it is much shorter than the planning territory via Entlebuch and so has less of an impact on the ground, the natural environment and the landscape, requires less construction material and has lower energy losses and costs.
Two sections are considered separately
The section between Mettlen and Hellbühl (Littau) is considered separately. It was upgraded to 380 kV in 1990, but is currently operating at just 220 kV. The Innertkirchen – Mettlen and Bickigen – Mettlen lines approach one another to the west of Rothenburg, from where they are bundled in the section to Mettlen. With this in mind, it makes sense to consider both lines together in this section in order to provide permanent relief for the settlement area. Swissgrid will therefore review the line routing in this area as part of the planned Bickigen – Mettlen line renovation. The line lead-in for the Innertkirchen substation will be considered separately within the Innertkirchen – Mettlen sectoral plan process: two additional transmission lines run parallel to the Innertkirchen – Mettlen line along a roughly two-kilometre section. As all three lines pass through the settlement area, the only option in this section is to install an underground cable in a tunnel.
In the next stage of the sectoral plan process, a monitoring group appointed by the Swiss Federal Office of Energy (SFOE) will come together with the federal authorities, the affected cantons and environmental associations to discuss and assess the planning territory options developed by Swissgrid. The monitoring group’s recommendation will then be taken forward to the public consultation stage. The Federal Council is expected to decide on the planning territory between Innertkirchen and Mettlen by autumn 2023. Swissgrid will then set out various planning corridors for each transmission technology (overhead line, underground cable or combined versions) within this planning territory and submit these to the SFOE monitoring group. The corridor will then be stipulated by the Federal Council. Ideally, the renewal of the Innertkirchen – Mettlen extra-high-voltage grid will be completed by 2035. After that, the existing line, parts of which run through the settlement area, will be removed.